Fixed #31055 -- Made constraint checks support databases aware.

django/db/models/base.py

@@ -1255,6 +1255,7 @@ class Model(metaclass=ModelBase):
     def check(cls, **kwargs):
         errors = [*cls._check_swappable(), *cls._check_model(), *cls._check_managers(**kwargs)]
         if not cls._meta.swapped:
+            databases = kwargs.get('databases') or []
             errors += [
                 *cls._check_fields(**kwargs),
                 *cls._check_m2m_through_same_relationship(),
@@ -1277,7 +1278,7 @@ class Model(metaclass=ModelBase):
                 *cls._check_unique_together(),
                 *cls._check_indexes(),
                 *cls._check_ordering(),
-                *cls._check_constraints(),
+                *cls._check_constraints(databases),
             ]
 
         return errors
@@ -1836,9 +1837,9 @@ class Model(metaclass=ModelBase):
         return errors
 
     @classmethod
-    def _check_constraints(cls):
+    def _check_constraints(cls, databases):
         errors = []
-        for db in settings.DATABASES:
+        for db in databases:
             if not router.allow_migrate_model(db, cls):
                 continue
             connection = connections[db]

tests/invalid_models_tests/test_models.py

@@ -6,7 +6,7 @@ from django.core.checks.model_checks import _check_lazy_references
 from django.db import connection, connections, models
 from django.db.models.functions import Lower
 from django.db.models.signals import post_init
-from django.test import SimpleTestCase
+from django.test import SimpleTestCase, TestCase
 from django.test.utils import isolate_apps, override_settings, register_lookup
 
 
@@ -1212,7 +1212,7 @@ class OtherModelTests(SimpleTestCase):
 
 
 @isolate_apps('invalid_models_tests')
-class ConstraintsTests(SimpleTestCase):
+class ConstraintsTests(TestCase):
     def test_check_constraints(self):
         class Model(models.Model):
             age = models.IntegerField()
@@ -1220,7 +1220,7 @@ class ConstraintsTests(SimpleTestCase):
             class Meta:
                 constraints = [models.CheckConstraint(check=models.Q(age__gte=18), name='is_adult')]
 
-        errors = Model.check()
+        errors = Model.check(databases=self.databases)
         warn = Warning(
             '%s does not support check constraints.' % connection.display_name,
             hint=(
@@ -1230,7 +1230,7 @@ class ConstraintsTests(SimpleTestCase):
             obj=Model,
             id='models.W027',
         )
-        expected = [] if connection.features.supports_table_check_constraints else [warn, warn]
+        expected = [] if connection.features.supports_table_check_constraints else [warn]
         self.assertCountEqual(errors, expected)
 
     def test_check_constraints_required_db_features(self):